Local Hotspots of Endemism or Artifacts of Incorrect Taxonomy? The Status of Microendemic Pill Millipede Species of the Genus Glomeris in Northern Italy (Diplopoda, Glomerida).

Thomas Wesener,Cathrin Conrad

doi:10.1371/journal.pone.0162284

Abstract

Local endemic species with their unique evolutionary history always stirred the interest of scientists. One such area especially rich in endemics is northern Italy. In case of pill millipedes of the genus Glomeris Latreille, 1803, only a single species is found in northern Europe, while 22 country-endemics alone are known from Italy. Many of these endemics, however, have not been studied in several decades; therefore we aimed to determine whether this diversity is the result of overlooked synonymies or natural processes. A focus was placed on the local endemics that are in some aspects morphologically similar to the widespread and variable G. klugii Brandt, 1833. The local endemics Glomeris larii Verhoeff, 1921, G. primordialis Verhoeff, 1930, G. oblongoguttata Verhoeff, 1894, G. oropensis Verhoeff, 1936, G. transalpina Koch, 1836, G. romana Verhoeff, 1900, G. ligurica Latzel, 1884 and G. apuana Verhoeff, 1911 were included in a molecular analysis incorporating ribosomal nuclear (28S) and mitochondrial (COI) genes. Individuals were sequenced and compared to 31 specimens from 18 localities of G. klugii. The final dataset included 657 base pairs for 56 terminals in the COI, and 14 terminals with 1068 base pairs in the combined 28S and COI analysis. Our analysis shows intraspecific distances of up to 5% in the COI gene in G. klugii that are not strictly correlated to geography or color pattern. G. larii is discovered to be genetically and morphologically identical to G. klugii and is synonymised with the latter. Interspecific distances in our dataset vary between 6.7 to 15.9%, with the lowest (6.7–9.0%) between G. primordialis and G. klugii. Our analysis confirms the species status of the local endemics G. primordialis, G. oblongoguttata, G. oropensis, G. transalpina, G. ligurica and G. apuana. We also confirm the synonymy of G. undulata Koch, 1844 under G. klugii. G. genuensis Latzel, 1886 is indistinguishable from G. ligurica.

Highlights

This study analyses the mitochondrial and nuclear genes of six Italian pill millipede species to determine whether the species are local endemics or the result of incorrect taxonomy
With the help of mitochondrial and nuclear genes, this study evaluates the taxonomic status of six more or less localized endemic Italian Glomeris species that historically belong to the G. klugii species-group: G. larii Verhoeff, 1921, G. primordialis Verhoeff, 1930, G. oblongoguttata
For the study of the northern Italian local endemic species, we selected specimens of G. larii, G. primordialis, G. oblongoguttata, G. oropensis, G. transalpina, G. romana, G. ligurica Latzel, 1884 and G. apuana Verhoeff, 1911; the sequences of G. ligurica and G. apuana came from earlier studies [11]

Summary

Introduction

This study analyses the mitochondrial and nuclear genes of six Italian pill millipede species to determine whether the species are local endemics or the result of incorrect taxonomy. The highest genus-level diversity of the Glomerida is in Europe [1,4]. The most species-rich European genus, Glomeris Latreille, 1803 [4,5], includes more than 70 species described from Europe and North Africa [6,7]. Thirty-five of these species are found in Italy and the highest species-level diversity in Europe is reached in Italy just south of the Alps [6,8]. Is home to more endemic pill millipede species than in all other European countries combined. Of Glomeris species endemic to Italy, 18 occur exclusively in northern Italy [6] and are often only known from a localized area, sometimes just the type locality. The species included in our study are six of the 22 endemic Glomeris species occurring in Italy [9,10,11]

Objectives

Methods

Results

Discussion

Conclusion